Mobile screening apparatus used in quarries and surface mining often make use of a number of superimposed decks. Each deck incorporates a screen of a different mesh size so that material to be screened can be divided into different sizes. The decks are usually located in a screen box. A number of conveyors can be operatively engaged with different decks to extract aggregate of different sizes depending on the location of those conveyors. The conveyors dump the aggregate into separate stockpiles.
Typically, the decks are usually horizontal or inclined for gravity-assistance. Also, the decks vibrate to enhance the screening process.
Generally, a heavy-duty crusher carries out an initial crushing process on the rock. The crushed material is then fed into a feed box and from there into the screen box. Oversize material can then be discharged into a stockpile or fed back to the crusher. Alternatively, any aggregate needing grading can be fed into the feed box.
In general, mobile screening apparatus include a centrally located power plant that is used to drive a hydraulic system for driving tracks, vibratory screen motors and possibly other equipment.
To date, mobile screening apparatus and equipment have not kept volumetric pace with larger crushing machines. As a result, a significant amount of demand has been placed on the production capacity of mobile screening apparatus, particularly the top deck of such apparatus. In most cases, the design has not changed, with the emphasis still on a major feed bin that is used to feed raw or unscreened material on to the top deck as well as recycled oversize material.
The inventor/s have found that operators spend a significant amount of time arranging various heights of conveyors and other machines, such as crushers and auxiliary screens so that they can feed material to each other. This can waste time and be costly.
At present, contractors are often required to add auxiliary screens to crushing plants to achieve a better transition from crusher to screening apparatus. However, these screens have difficulty in accommodating the material from the crushers.
Operators are required, in some cases, to add link conveyors between the crushers and the screen apparatus to enable a recycling feature. This results in additional costs and time spent in set up and additional power and fuel usage.